Check if performance gain can be achieved with different price querying

[21isenough]

Actual Behavior: Currently the bitcoin price is fetched once the first coin has been inserted.

Expected Behavior: Might gain some response time if the price is fetched in a regular interval rather than after the first coin.

[kimasplund]

Would it not be better if price is fetched at first coin insert, but fetched again and locked in on send?